Help executing a package procedure in SYS account; identifier must be declared

Help from anybody will be greatly appreciated. I have been trying to execute this package procedure by James Koopmann;

http://www.databasejournal.com/featu...r---Part-I.htm

I ran the package script on CTRL_SCHEMA_USER in "SYS" account, and then tried to call the "CREATE_USER" procedure in the same "SYS" account as follows;
SQL>exec CTRL_SCHEMA_USER.CREATE_USER(XM);

Oracle keeps telling ME that the "XM" identifier must be declared. Can somebody help me solve this problem? Thanks

Sorry, I got it now. I forgot to surround the string literal XM by single quote charaters as 'XM'. But then, you will still get error; cannot grant QUOTA on the tablespace. Just make sure that you are not granting QUOTA UNLIMITED to temporary tablespace if you are using 10gRel2.